Proteins are basic building blocks of life. To man, mammals, fowl, fish, and reptiles, proteins are an essential component of a healthy diet. Protein deterioration and putrefaction from spoilage limits the effective and efficient use of available resources. For example, raw animal protein generally putrefies and spoils within hours when left at room temperature. Through the years, methods such as salting, drying, canning, refrigeration, modified atmosphere packaging, and food irradiation have been developed to preserve or enhance the shelf-life of animal proteins.
Even with these advances in protein preservation mentioned, the need as well as the goal to improve methods and techniques to preserve protein while maintaining a protein's functional and nutritional qualities, continues in the academic and business world. And with an ever-increasing world population requiring more and more protein, innovation and invention in this field is increasingly important economically and environmentally.
Numerous attempts and extensive research for more than 60 years has gone into the development of a commercially acceptable method for enzymatically hydrolysing proteinaceous raw material such as meat, fowl, fish, and their by-products. For example, U.S. Pat. Nos. 7,070,953 to Bjarnason et al.; 6,803,062 to Yamamoto et al.; 6,372,282 to Edens et al.; 6,056,981 to Saxby; 5,985,337 to Blortz et al.; 5,607,840, to Van Gorp et al.; 5,356,647 to Loosen et al.; 5,053,234 to Anderson et al.; 4,976,973 to Shirakawa et al.; 4,863,746 to Uchida et al.; 4,361,586 to Meinke; 4,293,571 to Olofsson et al.; 4,176,199 to Vollmer et al.; 3,970,520 to Feldman et al.; 3,928,630 to Perini; 3,796,811 to Huth et al.; 3,561,973 to Rutman; 3,249,442 to Keyes et al.; 3,071,468 to Docken; 2,651,647 to Greenfield; 2,350,811 to Percheron; and Russian Patent No. 441,915 all disclose methods (with the exception of 2,651,647 to Greenfield) by which animal proteins are enzymatically hydrolysed to produce digested protein products. However, the methods disclosed in these patents have particular disadvantages and none are ideal. For example, the methods of U.S. Pat. Nos. 5,356,637, 5,607,840, 5,985,337, 6,056,981, and 6,803,062 require digestion times exceeding 4 hours. While the method of U.S. Pat. No. 6,056,981 uses no external enzymes, relying on autolysis, and the method of U.S. Pat. No. 7,070,953 relies primarily on cod proteases, in both cases the scope and utility value of the resulting methods are restricted relative to the present invention.
The present invention addresses, inter alia, certain improvements to methods and apparatus disclosed in U.S. Pat. Nos. 5,053,234 and 5,133,755 to Anderson et al., both incorporated herein by reference in their respective entireties. Specifically, the improvements disclosed herein provide methods and apparatus that can be used to produce partially hydrolysed particulate proteinaceous product under conditions of reduced process interruptions. The instant methods and apparatus provide greater fluidity and lubricity of the raw material as it is being processed to reduce clogging and to improve process efficiency. The instant methods and apparatus also provide improved efficiency of heat transfer into the raw material to reduce energy costs. The instant methods and apparatus also provide increased efficiency of proteolytic reactions performed on the raw material. The instant methods and apparatus produce a hydrolysed proteinaceous product that is free of steam contaminants. The instant methods and apparatus also provide improved control of the level of oil in the partially hydrolysed proteinaceous product.